[27.09] Terrestrial Planet Formation Around Close Binary Stars

Most stars reside in multiple star systems; however,
virtually all models of planetary growth have assumed an
isolated single star. Numerical simulations of the collapse
of molecular cloud cores to form binary stars suggest that
disks will form within such systems. Observations indirectly
suggest disk material around one or both components within
young binary star systems. If planets form at the right
places within such circumstellar disks, they can remain in
stable orbits within the binary star systems for eons. We
are simulating the late stages of growth of terrestrial
planets around close binary stars, using a new, ultrafast,
symplectic integrator that we have developed for this
purpose. The sum of the masses of the two stars is one solar
mass, and the initial disk of planetary embryos is the same
as that used for simulating the late stages of terrestrial
planet growth within our Solar System and in the Alpha
Centauri wide binary star system. Giant planets are included
in the simulations, as they are in most simulations of the
late stages of terrestrial planet accumulation in our Solar
System. When the stars are of equal mass and travel on a
circular orbit with semimajor axis of up to 0.1 AU, the
planetary embryos grow into a system of terrestrial planets
that is statistically identical to those formed about single
stars, but a larger semimajor axis and/or a significantly
eccentric binary orbit can lead to terrestrial planet
systems that contain fewer planets and/or are more
dynamically excited.